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Publication #ENY813

Grasshopper, Katydid and Cricket Pests of Florida Citrus1

T. R. Fasulo and R. F. Brooks2

Grasshoppers

Introduction

Several grasshopper species are sporadic problems in citrus groves. However, only the eastern lubber grasshopper, Romalea guttata (Latreille), and the American grasshopper, Schistocera americana (Drury), are of economic importance.

All grasshoppers have similar life histories. The female usually deposits her eggs in the soil. After hatching, the young nymphs look like adults but have no wings. They generally molt five to six times before reaching the adult stage, thus passing through five nymphal stages or instars. The adult grasshopper usually has wings and is able to fly.

Eastern Lubber Grasshopper

Physical Description

The eastern lubber grasshopper, which at times can be a serious pest of young citrus groves, is approximately 2 to 2 1/2 inches long when fully grown. The adult is a brilliant yellow with red and black markings and is incapable of flight. The nymphs (Figure 1) are almost solid black with yellow, and occasionally red, markings.

Figure 1. 

Eastern lubber grasshopper nymph.


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Life History

The eastern lubber grasshopper overwinters as eggs, which are laid in the soil along the margins of low, marshy areas. The eggs hatch the following spring and the nymphs migrate to the cover crop in adjacent citrus groves. This migration often results in feeding by large numbers of this pest, causing severe defoliation of young trees and occasionally even feeding on the bark of older trees. There is only one generation per year.

American Grasshopper

Physical Description

The American grasshopper (Figure 2), approximately 1 3/4 inches long when fully grown, is light brown with black markings.

Figure 2. 

American grasshopper adult.


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Life History

The American grasshopper overwinters as an adult in dense cover crop or brush. There are two generations per year. Oviposition often occurs in recently cultivated land. Eggs are commonly laid in small patches of Bermudagrass, which usually remain after disking or in miscellaneous weeds growing following cultivation. However, fallow land and pine tree plantations were the principal sources of infestation during the 1991-1992 outbreaks in central Florida.

Grasshopper Damage

Most of the damage by grasshoppers is caused by the nearly full grown nymphs of both grasshopper species. Adults do relatively less feeding than nymphs, especially just after completing the final molt. Most of the feeding occurs during the mid to late morning. Grasshoppers and katydids feed primarily on the foliage of citrus trees. However, fruit (Figure 3) is occasionally eaten. Foliage feeding on larger trees is usually insignificant, but severe defoliation can occur on young trees. Both groups of insects sometimes feed on the peel of growing oranges, resulting in large, smooth, sunken areas in the rind as the fruit develops. Some crickets also produce similar damage. Some of the fruit will drop, but others will remain on the tree with unsightly blemishes.

Figure 3. 

Grasshopper damaged fruit.


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Management Recommendations

Cultural and Biological Control

Clean cultivation acts as a deterrent to local oviposition by the American grasshopper and reduces the number of nymphs that survive after hatching due to the effects of heat and loss of suitable host plants. In groves where grasshoppers are expected in spring, cultivation must be started prior to the first of March and continued through the middle of May. Clean cultivation after about August 15 tends to prevent the survival of second generation nymphs of the American grasshopper. Thorough disking will kill most nymphs, which are less than 1/2 inch long. Disking or chopping when the grasshoppers are half grown is counter-productive as they will migrate up onto adjacent citrus trees. In both young and old groves it has been noted that a heavier fruit crop is correlated with larger numbers of grasshoppers.

Extended periods of wet weather contribute to a decline in future populations. The wet weather provides better conditions for parasitic fungi that attack developing eggs laid in the ground.

Chemical Control

If chemical control is warranted, only coverage of the outside canopy using 50 to 100 gallons of spray per acre is necessary. The lower two-thirds of the tree canopy and adjacent cover crop should receive most of the spray. Consult the latest copy of the Florida Citrus Pest Management Guide for recommended insecticides.

Detailed information on the American and eastern lubber grasshoppers, as well as color photographs, is available on the University of Florida Featured Creatures WWW site at http://entomology.ifas.ufl.edu/creatures/.

Katydids

Introduction

Although at least two other species of katydids are found in Florida citrus groves, only the broadwinged katydid (Figure 4), Microcentrum rhombifolium (Saussure), is of any economic importance.

Figure 4. 

Broadwinged katydid.


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Physical Description

This katydid is approximately 2 to 2 1/2 inches long, bright green, and has veined wings that resemble citrus leaves.

Life History

The overwintering eggs (Figure 5) initially hatch during the spring flush. There are several generations per year in Florida resulting in increasing populations from June through September. Almost all stages can be found at any time during this period. This species can go from egg to sexually mature adult in about three months. The eggs are rather easy to identify as they are laid along leaf margins in rows usually in large trees. The eggs are heavily parasitized by a small wasp, Anastatus mirabilis (Walsh & Riley), which makes a small round exit hole when the adult wasp emerges from the katydid egg. Katydid populations have been observed to be smaller following cold winters.

Figure 5. 

Katydid eggs.


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Damage

Katydids feed on the foliage (Figure 6) of citrus trees. Most of the feeding occurs during the mid to late morning. Foliage feeding on larger trees is usually insignificant, but severe defoliation can occur on young trees. Katydids, like grasshoppers, sometimes feed on the peel of growing oranges (Figure 7), resulting in large, smooth, sunken areas in the rind as the fruit develops. Some of the fruit will drop but others will remain on the tree with unsightly blemishes. Although this damage is commonly called "katydid damage," it can also be caused by grasshoppers, crickets, and other insects.

Figure 6. 

Katydid damaged foliage.


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Figure 7. 

Oranges damaged by grasshopper and katydid feeding.


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Management Recommendations

Chemical control recommendations for katydids are the same as those for grasshoppers.

Crickets

Introduction

Crickets are sometimes numerous in citrus groves. The restless bush cricket, Hapithus agitator Uhler, has been shown to feed on citrus foliage and small fruits but is found principally in ground cover rather than in the trees. Its damage is confined to the lower canopy. A related species, the false jumping bush cricket, Orocharis luteolira Walker, lives in the canopy but remains concealed during the day and feeds at night. Its food habits are similar to the restless bush cricket and it probably accounts for some damage to small fruit.

Detailed information on many cricket species is available on the University of Florida Featured Creatures website at http://entomology.ifas.ufl.edu/creatures/.

Damage

Fruit injury may occur anytime between petal fall and before fruit reaches 1/2 inch diameter. The extent of peel blemish (Figure 8) at maturity will depend upon the amount of injury which occurs on the small fruit. If injury is sufficiently severe, the fruit will drop. Lesser feedings result in a range of damage from lopsided fruit growth to minor peel blemish. Cricket feeding on large green fruit results in large areas of rasped peel. Foliage injury is characterized by holes eaten in the center of leaves as well as along the margins. Crickets also feed on young twigs (Figure 9).

Figure 8. 

Peel blemish caused by cricket feeding.


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Figure 9. 

Young twigs showing cricket feeding damage.


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Management Recommendations

Consult the latest copy of the Florida Citrus Pest Management Guide for recommended insecticides.

Footnotes

1.

This document is ENY-813, one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: December 1994. Revised: June 2004 and July 2009. Reviewed August 2012. Please visit the EDIS website at http://edis.ifas.ufl.edu and the Department of Entomology and Nematology website located at http://entnemdept.ifas.ufl.edu/.

2.

T. R. Fasulo, senior associate in entomology, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611, and R. F. Brooks, retired professor, Citrus Research and Education Center, Lake Alfred, FL .


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.